1. Field of the Invention
This invention relates to a combustion type heater, for vehicles, that is used for heating the inside of vehicles such as cars.
2. Description of the Related Art
Combustion type heaters for vehicles, used for heating the inside of the vehicles, generally employ the following construction. A blower driven by a motor introduces combustion air into a combustion chamber, and a fuel pump supplies a fuel into the combustion chamber. Air and the fuel are mixed inside the combustion chamber to create an air-fuel mixture. A glow plug ignites the air-fuel mixture. The resulting combustion heat heats flowing air or water, and the air or the water so heated, in turn, heats the inside of the car.
A heat exchanger for a car heater described in Japanese Unexamined Utility Model Publication (Kokai) No. 6-16112 is known as a combustion type heater for a vehicle of the type described above. As shown in FIG. 15 of the accompanying drawings, the heat exchanger 1 for a heater of a car (combustion type heater) includes therein an air chamber 2 for passing combustion air and a combustion chamber 3 for burning an air-fuel mixture. The heat exchanger 1 further includes, inside the air chamber 2, a motor 4 and a blower 5, for the combustion air, rotated by the motor 4. When the motor 4 drives the blower 5, air is introduced into the combustion chamber 3 through an air passage 2-1. A glow plug 6, the distal end of which protrudes into the combustion chamber 3, is. fitted to an outer wall of the heat exchanger 1. A fluid passage 7 through which a fluid for heat exchange flows is disposed inside the outer wall. A fuel pump 8 is disposed separately from the heat exchanger 1. Fuel piping 9 is disposed in such a manner as to extend from the fuel pump 8 to the combustion chamber 3. A planar wick 10 is disposed at a bottom 12 of the combustion chamber 3 and is connected to the distal end of the fuel piping 9.
The fuel sent from the fuel pump 8 is diffused by the wick 10, and is mixed with combustion air blown by the blower 5 to create the air-fuel mixture. The glow plug 6 ignites and burns this air-fuel mixture.
In the conventional heat exchanger 1 for the car heater described above, the fuel piping 9 is positioned at the center of the planar wick 10, and the fuel is supplied from the center part of the wick 10. According to this method, however, the fuel sinks into the wick 10 from the center and gradually diffuses to the whole part as typically shown in FIG. 16. Therefore, it takes time for the fuel to evaporate from the wick as a whole, and the rise time of the operation of the heat exchanger for the car heat is retarded.
In this heat exchanger for the car heater according to the prior art, the fuel distribution in the wick is dense at the center and is leaner towards the ends even during steady combustion, generating thereby non-uniformity in fuel evaporation. When the feed amount of the fuel is great, the fuel sometimes scatters while flowing through the wick.
In this conventional heat exchanger for the car heater, only one glow plug 6 is disposed in the proximity of the planar wick 10. The wick is heated by the radiation energy of the glow plug to evaporate the fuel, and the evaporated fuel is ignited by the glow plug. Moreover, the glow plug 6 is inserted into the combustion chamber 3 while penetrating through the combustion gas passage. According to this arrangement of the glow plug, about a half of the radiation energy of the glow plug is lost, a long time is necessary for the fuel to evaporate% from the wick, and the start of the operation of the heat exchanger for the car heater is retarded.
In the conventional combustion type heater described above, the combustion chamber is disposed in the longitudinal direction. A combustion type heater wherein the combustion chamber is disposed in the transverse direction is also known as described, for example, in Japanese Unexamined Patent Publication (Kokai) No. 7-215043. In this conventional combustion type heater 1 for vehicles wherein the combustion chamber 3 is disposed transversely (see FIG. 17), the fuel supplied from the fuel piping 9 to the wick 10 as an evaporation plate diffuses through the wick 10 as a whole due to capillary action. However, the fuel that cannot fully evaporate drops gradually to the lower part of the wick 10 due to gravity. In consequence, the fuel density is high at the lower part of the wick and the fuel forms a pool. In an extreme case, the pooled fuel flows out into the combustion chamber of the combustion cylinder. When the fuel pool is generated, the pooled fuel gradually permeates and diffuses into the wick and evaporates after put-off of the heater, and is likely to be discharged while it remains as the unevaporated fuel. When the fuel flows out into the combustion chamber, the air-fuel ratio becomes rich during combustion, thereby inviting deterioration of exhaust emission.
To solve these problems, the combustion type heater 1 disclosed in Japanese Unexamined Patent Publication (Kokai.) No. 7-215043 employs the-construction wherein the wick 10 is extended inside the combustion chamber at its lowermost outer peripheral edge as shown in FIG. 17. According to this construction, the extension part lOa of the wick 10 receives radiation heat and is always heated by the flame of the combustion chamber 3, and its heat is transferred to the fuel gathering at the lowermost position. Therefore, even when the fuel, that sinks into the wick 10 but cannot fully evaporate, sinks due, to gravity and gathers at the lowermost position of the wick 10, its evaporation is promoted, the occurrence of the fuel pool can be prevented, and discharge of the non-burnt fuel and deterioration of exhaust emission can be avoided.
In the conventional combustion heater described above, however, evaporation of the fuel at the lowermost position of the wick 10, that is, the fuel pooled at the lowermost part of the combustion chamber, is promoted. Therefore, mixing of the fuel and combustion air does not become uniform between the upper and lower portions of the combustion chamber 3, and the evaporated fuel becomes rich at the lower portion. Consequently, complete combustion is not attained at the lower portion of the combustion chamber, so that soot is generated and exhaust emission gets deteriorated. Furthermore, the fuel does not diffuse through the wick as a whole due to the influence of gravity but a greater amount flows towards the lower portion. Thus, there are other problems in that a long time is necessary for the fuel to evaporate from the wick and the start of the operation of the combustion type heater is retarded.
In view of the problems described above, it is an object of the present invention to shorten a diffusion time of a fuel to the entire part of a wick as well as a heating time of the wick itself, and to quickly activate a combustion type heater.
It is another object of the present invention to prevent the occurrence of a fuel pool at the lowermost position of a wick, to make uniform a mixing ratio between an evaporated fuel and combustion air throughout a combustion chamber, and to improve the exhaust emission.
According to one aspect of the present invention, there is provided a combustion type heater including fuel distribution means for dispersing a supplied fuel to the whole surface of a wick. After the start of the supply of the fuel, the fuel is quickly supplied to the whole surface of the wick, combustion starts occurring from the whole surface of the wick immediately after ignition, and the start of the operation of the combustion type heater can be earlier.
According to another aspect of the present invention, there is provided a combustion type heater including a glow plug for ignition, disposed in the proximity of a front surface of a wick, and a glow plug for heating the wick, so disposed as to keep contact with the wick. The energy of the glow plugs can be utilized effectively for heating the wick, the wick can be quickly heated as a whole, and combustion quickly takes place from the whole surface of the wick.
According to still another aspect of the present invention, there is provided a combustion type heater including a planar heater for heating a wick, so disposed as to keep contact with the wick. The wick can be efficiently heated as a whole, the fuel quickly evaporates from the whole surface of the wick, and combustion starts occurring from the whole surface of the wick.
According to still another aspect of the present invention, there is provided a combustion type heater including a wick so disposed as to keep contact with a bottom surface of a combustion chamber, and a ring-like groove defined in the bottom surface of the combustion chamber in such a manner as to encompass a fuel feed port formed in the bottom surface of the combustion chamber. Even when the combustion chamber is arranged transversely, this construction can prevent the fuel from pooling at a lower part of the combustion chamber as the lowermost position of the wick due to the influence of gravity, and the fuel can spread substantially uniformly over the entire wick. In consequence, the combustion proceeds satisfactorily, deterioration of exhaust emission can be prevented, and the start of the operation of the combustion type heater can be improved.
The present invention may be more fully understood from the description of preferred embodiments of the invention, as set forth below, together with the accompanying drawings.